The invention is in the field of Silicon-On-Insulator (SOI) devices, and relates specifically to complementary lateral insulated gate rectifiers for use in power circuit applications such as the electronic control of discharge lamps.
Known power control circuits frequently use a half-bridge configuration, with two identical switching transistors connected in series, with the source of one transistor connected to the drain of another to form a common output terminal. This type of configuration is typically used for integrated power circuits, because the required voltage rating of the transistors is lowest. Nevertheless, there are certain disadvantages to this configuration. For example, one transistor operates as a source follower, with an inherently higher "on" resistance than a common-source configuration and lower breakdown voltage to substrate when using standard constructions. While these disadvantages may be overcome, for example by using the source follower structure shown in U.S. patent application Ser. No. 766,665, the resulting structure will be more complex and difficult to fabricate.
Another solution, typically used for discrete component circuits, uses complementary MOS FET devices in a common-drain configuration. However, such a configuration is not practical in an integrated configuration, because of fabrication difficulties and because the two devices, if integrated, would have substantially different "on" resistances, thus resulting in an unbalanced output waveform.
These disadvantages are overcome, in accordance with the invention contained in my co-pending U.S. patent application Ser. No. 945,470, entitled COMPLEMENTARY LATERAL INSULATED GATE RECTIFIERS and incorporated herein by reference. That application discloses a complementary MOS Lateral Insulated Gate Rectifier (LIGR) configuration which is suitable for use in power circuit configurations, which can be easily and inexpensively integrated, and which has two complementary switching devices with comparable "on" resistances.
Nevertheless, it would be desirable to obtain an LIGR construction having a simpler structural configuration, and in which substrate currents which could affect switching characteristics and control functions in a power IC device are substantially eliminated.